/*
* Copyright 2004-2023 H2 Group. Multiple-Licensed under the MPL 2.0,
* and the EPL 1.0 (https://h2database.com/html/license.html).
* Initial Developer: H2 Group
*/
package org.h2.expression;
import org.h2.engine.SessionLocal;
import org.h2.value.TypeInfo;
import org.h2.value.Value;
import org.h2.value.ValueNull;
/**
* A searched case.
*/
public final class SearchedCase extends OperationN {
public SearchedCase() {
super(new Expression[4]);
}
public SearchedCase(Expression[] args) {
super(args);
}
@Override
public Value getValue(SessionLocal session) {
int len = args.length - 1;
for (int i = 0; i < len; i += 2) {
if (args[i].getBooleanValue(session)) {
return args[i + 1].getValue(session).convertTo(type, session);
}
}
if ((len & 1) == 0) {
return args[len].getValue(session).convertTo(type, session);
}
return ValueNull.INSTANCE;
}
@Override
public Expression optimize(SessionLocal session) {
TypeInfo typeInfo = TypeInfo.TYPE_UNKNOWN;
int len = args.length - 1;
boolean allConst = true;
for (int i = 0; i < len; i += 2) {
Expression condition = args[i].optimize(session);
Expression result = args[i + 1].optimize(session);
if (allConst) {
if (condition.isConstant()) {
if (condition.getBooleanValue(session)) {
return result;
}
} else {
allConst = false;
}
}
args[i] = condition;
args[i + 1] = result;
typeInfo = SimpleCase.combineTypes(typeInfo, result);
}
if ((len & 1) == 0) {
Expression result = args[len].optimize(session);
if (allConst) {
return result;
}
args[len] = result;
typeInfo = SimpleCase.combineTypes(typeInfo, result);
} else if (allConst) {
return ValueExpression.NULL;
}
if (typeInfo.getValueType() == Value.UNKNOWN) {
typeInfo = TypeInfo.TYPE_VARCHAR;
}
type = typeInfo;
return this;
}
@Override
public StringBuilder getUnenclosedSQL(StringBuilder builder, int sqlFlags) {
builder.append("CASE");
int len = args.length - 1;
for (int i = 0; i < len; i += 2) {
builder.append(" WHEN ");
args[i].getUnenclosedSQL(builder, sqlFlags);
builder.append(" THEN ");
args[i + 1].getUnenclosedSQL(builder, sqlFlags);
}
if ((len & 1) == 0) {
builder.append(" ELSE ");
args[len].getUnenclosedSQL(builder, sqlFlags);
}
return builder.append(" END");
}
}